Enter Catty Corner Vault Location in the Fortnite
For one of the Week 1 challenges in Fortnite (Chapter 2 / Season 3) you need to "Enter Catty Corner Vault" to complete one of the challenges.
This is the same process as opening vaults as the previous season. Simply head to Catty Corner, and look for the boss walking around the map. Defeat him and you'll get the keycard.
Now bring this keycard to the vault, the location of which is shown in this video below.